Thetis, one of the Nereids, was brought up by Hera.
Both Zeus and Poseidon
fall in love with her, but an oracle prophesied that the son born to Thetis
would be more powerful than her father. Thus the gods hurried to marry
her off to a mortal. She was married to Peleus, king of Phthia, and gave
birth to
Achilles. She left Peleus,
but never lost interest in her son, whom she helped and gave advice all
his short life.
See: Jean-Auguste-Dominique Ingres. Jupiter
and Thetis.